A nano SIM is a nano SIM is the same size however with Verizon they typically like to change out the SIM card when you bring a device from another carrier to then which makes sense. So I'm glad Verizon got your phone to work best of luck.

If the SIM cards are the same size and on the same carrier you can use it in a phone where it requires the same size SIM however you cannot use a Verizon sim in a T-Mobile phone with T-Mobile service nor vice versa.

Also note that the Galaxy S7 on Verizon is different than T-Mobile version as T-Mobile does not have CDMA technology and is gsm whereas Verizon does not use GSM.